The wetting of a surface of a solid such as e.g. a polymer material, silicon, a metal or an alloy by a liquid indicates an interaction between the surface of the solid and a molecule of liquid (adsorption of liquid to the surface of a solid), and a competitive phenomenon of adhesion between the solid and liquid and cohesion between molecules of the liquid. A larger cohesion than adhesion brings about a decrease in wettability, and less cohesion than adhesion brings about an increase in wettability.
Good wettability to liquid water refers to hydrophilic properties, and poor wettability refers to hydrophobic properties.
Such wettability can be quantitatively determined by measuring a contact angle of a solid surface. The hydrophobic properties mainly depend on chemical properties of the surface and of the micro- and nano-structures thereof.
Various methods have been reported (e.g. in US 2007/0013106A1) to construct hydrophobic surfaces by modifying structures of the surfaces. Conventionally, hydrophobic surfaces are fabricated with the help of chemical treatment for changing the surface energy of materials or for modifying the surface roughness, for example by polypropylene etching, plasma enhanced chemical vapor deposition (PECVD), plasma polymerization, plasma fluorination of polybutadiene, microwave anodic oxidation of aluminum, solidification of an alkylketene dimer, nanostructuring carbon film, polypropylene coating, carbon nanotube aligning, forming poly(vinyl) alcohol nanofibers, making the surface of polydimethylsiloxane porous, or oxygen plasma treatment. US 2007/0013106 A1 in particular disclose a UV-nanoimprint lithography technique to produce a hydrophobic structure in a polymer film based on replicating the structure of a hydrophobic leaf, e.g. lovegrass leaf.
In Life Science diagnostics in order to analyze e.g. proteins, the proteins are solved in a liquid, also referred to as crystallization matrix and afterwards a droplet of the combination of crystallization matrix and protein, also referred to as analyte is applied on a surface of a substrate. The crystallization matrix evaporates and the protein/matrix alloy crystallize on the surface of the substrate. The crystallized proteins are then analyzed via e.g. a mass spectrometric process.
Known crystallization matrices have compounds like e.g. 2,5-dihydroxy benzoic acid, 3,5-dimethoxy-4-hydroxycinnamic acid, 4-hydroxy-3-methoxycinnamic acid, α-cyano-4-hydroxycinnamic acid, picolinic acid or 3-hydroxy picolinic acid and their respective solvents and applications are depicted in FIG. 7, which also show the used wavelength in the ultraviolet (UV)-region used for analytic purposes. Further matrices might be used as well, e.g. a polymer research matrix called “Dithranol”.